<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        h1 {
            color: red;/* 颜色关键字写法 */
            color: rgb(0, 255, 0);/*rgb写法,数值0-255*/
            color: rgba(0, 255, 0, 0.5);/*rgba写法第四个数值为0-1*/
            color: #0000ff;/*十六进制写法*/
        }
    </style>
</head>
<body>
    <h1>h1标签</h1>
</body>
</html>